tick_setup_device in tick-common.c

[chao xie <xiechao.linux@gmail.com>]

hi
I am very strange about this function.
In this function, it has
/*
         * When the device is not per cpu, pin the interrupt to the
         * current cpu:
         */
        if (!cpumask_equal(newdev->cpumask, cpumask))
                irq_set_affinity(newdev->irq, cpumask);

When the clock event device has cpu_mask set to be cpumask_of(1), it
means that the device is bound to cpu1. So above code has covered it,
but why we have "!cpumask_equal(newdev->cpumask, cpumask)"?
if the "newdev->cpumask" equals "cpumask", cpumask_equal will return
1, and at this situation we will set the irq affinity because the
device is bound to the dedicated cpu.

Is there a bug, or i understand wrong about cpumask of clock_event_device?
Thanks.